Chosen Solution
Computer was working fine but was running slow and I had also just replaced the battery and trackpad with non Apple parts so I decided to do a PRAM reset, now the computer won’t start at all. Will not boot in safe mode, or let me start while holding “O” or command + R. I tried another PRAM reset but still didn’t do anything. Update (10/07/2017) The computer was working after I installed the parts. I used it for an hour or so and everything seemed fine. The slowness I was experiencing was not new after the new parts, it was an existing problem, which prompted the pram reset and the following failure MacBook Pro “Core 2 Duo” 2.26 13" (SD/FW) 2.26 GHz Core 2 Duo (P7550*) Intro. June 8, 2009 Disc. April 13, 2010 Order MB990LL/A Model A1278 (EMC 2326*) Family Mid-2009 13" ID MacBookPro5,5 RAM 2 GB VRAM 256 MB Storage 160 GB HDD Optical 8X DL “SuperDrive” Complete MacBook Pro “Core 2 Duo” 2.26 13" (SD/FW) Specs
Try also reset the smc. After the smc reset do again Pram reset. I hope this can work for your case . You can try it, this might solve the problem. Also check your HDD that might be the point of failure.
